User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-GB; rv:1.8.1.1) Gecko/20061204 Firefox/2.0.0.1 Build Identifier: version 1.5.0.9 (20061207) Every few days or so, one or two, maybe three junk messages (out of maybe 5-20 in Junk) found in the Junk folder are not actually flagged as Junk. This means that when I use 'Delete Junk Context Menu' to delete all mail marked as junk, these messages don't get deleted. They are junk, but the junk flag is not being set. I'm accessing my mail via IMAP, and I can attach a sample message although the message source is not particularly significant in any way that I can see. Reproducible: Sometimes Steps to Reproduce: 1. Open Junk folder of an IMAP account 2. Look at the mail Actual Results: The odd message here or there does not have the Junk flag set Expected Results: All messages should be marked as Junk

Same as bug 366764? (Though this explains it better.) And obviously there is no server side filtering to junk? Is tb set to trust junk-headers from server side junk filters?

No server-side filtering, and no existing headers are being set to be heeded. Junk mail control is entirely left to Thunderbird.

FWIW, this is an IMAP bug. Now that I'm getting lots of spam in my POP3 account, it's clear that only IMAP mail is being affected by this.

are you also using thunderbird filter with action of "mark as junk"? Can you reproduce just as easily with thunderbird 3 beta? (backup your profile before using) http://en-us.www.mozillamessaging.com/en-US/thunderbird/early_releases/

Tb 2.0.0.21 (20090302) on POP3 has stopped marking spam as junk but still moves it to junk folder. It also doesn't add flag when i manually mark spam as junk, and it has also removed all old junk flags in the folder that were there before. It even removes flags (not immediately) when i mark messages in the junk folder. Interestingly, Tb does add the flags when the same messages in another folder in the same account are manually marked as junk, and the problem does not exist in the other accounts. I remember having had this problem in the past (but don't remember what got rid of it), and i remember seeing forum posts about it, but i couldn't find any bug report besides this one, and i couldn't find any interesting forum threads.

I found the more relevant bug 315272

I've long since lost track, honestly. I've been using 3.0b2 for a while, and I'm not seeing the problem any more.